Running on only two cylinders?

My bike seems to run alright, but I really don't have any thing to compare it to. The only PROBLEM I have with it is that it seems to lack power, especially at higher RPM or if if gun it. When I hit the throttle hard, it seems to sputter out, then I let off the throttle and it is fine and I can accelerate slowly again...

I was just out screwing around with my bike, letting it warm up and I sprayed some water on the headers, the two outside headers steam up like you would expect, but the two inside ones seem COLD. no steam. Also, just as a test I pulled the plug wires off the cold cylinders WHILE the bike was running and there NO difference in how it was running. Does this sound possible? I have ridden it like this for 100's of miles and just dealt with the sputtering problem, and it hasn't really bothered me too much.

If they are not working, any suggestions on how to get them working?

 

First check to see if it is the spark, gas, or compression. If it is the spark, it could be the plugs, coil, or ignition box(possibly the pick up, but I wouldn't think that would be the problem). Swap out plugs first. If it continues, check the coils. There are 2 coils on this bike. I am not sure which cylinders each coil uses, but if it is the center/outside and no spark, switch coils to see if the problem stays or moves with the coil. If it stays, you are probably looking at the ignition box. If the problem moves, you have a bad coil.

I have seen a bunch of the old XJ's on craigslist lately that are in need of the ignition modual.

No compression, it could just be a tight valve.

 

if its the 2 inside ones i dont think its a spark issue ( i could be wrong) i would bet you have some cracked boots and the inside cylinders are too lean to run.

 

naw, those two run of the same coil. Try the switch and see if the problem moves is good advice from C21.

 

I'll confirm that the #2 and #3 share a coil (the right side coil). They also share a pickup coil (under the left side crank-end cover) and they share one channel of the TCI. So, if you don't have spark there, it could be any of the three... it could also be something as simple as a bad plug cap, because the plugs on these bikes fire in series; so if one cap, plug, or wire is bad it can keep both of the plugs on that coil from firing.

If you're used to riding with only two cylinders, you're going to LOVE your bike when you get it running on all four.

 

I'm thinking fuel....what do the non firing plugs look like after a cold start? Are they wet?

 

Your poor bike is starving to be drivin like its meant to!!
If you havent changed spark plugs I'd say try it. Just cause. Two bucks a pop. Then try the coil method. Could be a dead coil. Those boots get cracked pretty easy. And if they crack, more air gets in. Less fuel. Not enough to fire. So try the simple things first!
-Chris

 

Thanks guy's I have been too busy to mess with it, but saturday I am going to have alone time to tear it down and see what's what...


thanks again, you guys are the best!

 

Mike, I'm just up the road if you need a hand! I've spare sets of coils for troubleshooting and can also repair most coil damage (however, burned out primary line is a done deal, it's dead).

 

Ok, I finally had a little time to play around with it.

spark plugs LOOK good.

can anyone tell me how I should test the coils? I tried just switching the spark plug wires from 1 & 4 to 2 & 3 and the bike just wouldn't start.

I tried swapping the wires that go TO the coils and had no results (bike wouldn't even start or turn over)

Are the coils on these connected in a firing order similar to a distributor cap on a car?


The only other thing I noticed that has me worried now is after trying to start it and actually riding it a little bit, I noticed a the smell of gas, and a puddle on the ground. I tracked it down and it looks to me like CARB #3 is completely flooded and overflowing with gas? I am no expert (duh) but in my imagination, all the gas that should be flowing through the carb was stopping in the carb and spilling out towards the rear of the motorcycle. I never noticed this kind of flooding before today, it could have been happening before but it sure seemed like a lot of gas.

 

Have you tried touching the spark plug to the cylinder head while turning over or running the bike to make sure you have spark? This is a very simple test that will answer your question of spark going to the plug.

 

If you swap BOTH (Grey swapped with Orange going TO the coils) AND (1/4 swapped with 2/3 at the plugs), then the bike should run as well as before, but any ignition problem from one coil would show up on the other set of plugs. In general, though, the 2/3 wires are a bit short to reach the 1/4 plugs.

Also, if you were unfortunate enough to have any two of: a bad TCI channel, a bad coil, or a bad pickup on the same ignition channel, though, then a swap like described would leave you with no ignition at all.

 

I would seriously look at your coils. I've noticed that they tend to crack between the steel core and the secondary ignition wire ports.
Follow SQLGuy's advice and troubleshoot.
As I mentioned, I'm right up the road with a spare set of everything needed to troubleshoot this.
You also should pull the carbs, clean and inspect them, particularly the float needles and seats.